1. Field of the Invention
This invention relates to rotatable selector switch assemblies, and more particularly to switch assemblies capable of completing discrete circuits turned to predetermined radio frequencies including printed circuits, in a module construction for providing a numerical display of the frequencies selected.
2. Description of the Prior Art
It has long been known to use selector switches employing rotary elements. The rotary element could be a printed circuit board or a printed wire board. Hereinafter in this specification, the terms "printed circuit board" and "printed wire board" shall be used interchangeably to indicate boards on which at least parts of electrical circuitry are etched or otherwise formed. Possibly, electrical component parts, such as resistors, capacitors, inductors, diodes, triodes and the like are mounted on the boards or electrically connected to the boards.
In cases where the rotary element contains such printed circuitry, common connected brush-type electrical contacts are positioned on stationary elements. Sundry switch connections are individually made as the rotary element is selectively turned. Alternatively, the circuitry on the rotary printed circuit board could provide the switch connections for otherwise open circuitry, having the brush contacts as leads.
Frequently the brush sets are mounted in modules having centers coaxial with the rotary element. A plurality of such printed circuits boards and brush modules in alignment provide for expanded switching capability. See, for example, McGee, U.S. Pat. No. 3,086,096 and Lockard, U.S. Pat. No. 3,809,830.
Other embodiments of such rotary switching constructions have a stationary printed circuit board. A rotary wheel having brush-type electrical contacts connects electrical circuits on the board as the wheel is selectively rotated. Most often the wheel is a thumbwheel. For a representative example of such construction, note Kendall, et al. U.S. Pat. No. 3,719,785. In some recent teachings, the wheel is turned by knobs connected to the shaft coaxial with the wheel. Representative of such construction would be Menard, U.S. Pat. No. 3,734,869 and MacDonald, U.S. Pat. No. 3,754,106.
Such switching assemblies have become more important in the effort to make radio transceivers and receivers more compact and portable. In some arrangements currently used as Citizen's Band (CB) radios, increased switching capability is desired and permitted by airwave regulations. In recent years, 23 channels were available and, since 1977, the number of channels was increased to 40. Increased switch circuitry may be added by the accumulative stacking techniques mentioned above. Such techniques are not ideal, however, because they necessarily require in the increase of circuitry, an almost proportional increase in bulk.
One teaching has the printed circuit board formed with circuit elements on both of its sides. Holes are provided connecting one side with the other. Connecting pins mechanically are inserted through the holes to form the switched connection. While interesting, the resulting assembly is still bulky and requires mechanically moving switch connectors.
It is desired to obtain a switch assembly having increased circuitry without the usually attandant increase in the number of modules or bulk. It is also desired to provide a switch assembly having virtually limitless numbers of switching connectors capable of variable circuit design connections.